Most manufactures don't install the plugs for the turbos to install a gauge because they don't think they'll ever exceed the turbine inlet temperature(TIT) rating, most modern turbos can handle over 1800 or 1900 degrees f sustained. Cummins performs their durability and burst tests for their turbos at around 2,800f, hence why they don't worry about the temperature in the real world. They monitor post turbo just for emission purposes.
I mainly stopped running the EGT gauge because I knew there's no way I'll go beyond the rating for my turbo(most modern turbos made after the mid 2000s are rated to over 1800 degrees sustained), especially after talking to one of the engineers who performs the destructive testing for BW. I'm running a modern BW turbo and have buried the 2000 degree EGT gauge that was on it for over a minute at a time when towing up a long grade. I just watch the water temperature instead, that's the tell tale for when you're about to break something. I installed a thermocouple in the factory PD140 EGT port and and made an arduino digital readout for my '06. I couldn't get that thing to budge much farther than 1800 when blasting up one of the grades, so I removed it to keep a clean looking interior.
For analyzing pre turbo and post turbo, I recommend going for a ride in a CR TDI. They do have a total of 4 EGT gauges I believe. Pre turbo, post turbo, pre DPF and post DPF if I recall correctly. It was interesting watching the differences between pre and post turbo, at some points even when not regenerating, post turbo temp at low throttle would almost match pre turbo. The closer the turbo was to its efficient zone of the map, the greater the difference was between pre and post turbo. Mine was stock, so I never really had a chance to see the difference when running the turbo towards its limit.